U.S. patent application number 10/950776 was filed with the patent office on 2006-03-30 for ultrasound simulation apparatus and method.
Invention is credited to Anton Butsev, Weimin Wu.
Application Number | 20060069536 10/950776 |
Document ID | / |
Family ID | 35825337 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060069536 |
Kind Code |
A1 |
Butsev; Anton ; et
al. |
March 30, 2006 |
Ultrasound simulation apparatus and method
Abstract
A method includes receiving data values associated with one of a
position and orientation of a simulated scanner relative to an
object. Image values are calculated, substantially in real-time,
based on the data values. A simulated ultrasound image is rendered
in a graphical display based on the image values. The simulated
ultrasound image is representative of an interior or a simulated
interior of the object on the ultrasound scan plane.
Inventors: |
Butsev; Anton; (Burke,
VA) ; Wu; Weimin; (Boyds, MD) |
Correspondence
Address: |
David B. Ritchie;THELEN REID & PRIEST LLP
P.O. BOX 640640
SAN JOSE
CA
95164-0640
US
|
Family ID: |
35825337 |
Appl. No.: |
10/950776 |
Filed: |
September 28, 2004 |
Current U.S.
Class: |
703/6 |
Current CPC
Class: |
G01N 29/0609 20130101;
G01N 29/44 20130101; G06T 15/00 20130101; G01N 29/265 20130101;
G01N 29/27 20130101 |
Class at
Publication: |
703/006 |
International
Class: |
G06G 7/48 20060101
G06G007/48 |
Claims
1. A method, comprising: receiving a plurality of data values
associated with a position of a simulated scanner relative to an
object; calculating, substantially in real-time, a plurality of
image values based on the plurality of data values; and rendering a
simulated ultrasound image in a graphical display based on the
plurality of image values, the simulated ultrasound image being
representative of one of an interior and a simulated interior of
the object on the ultrasound scan plane.
2. The method of claim 1, wherein the rendering is performed via a
stencil buffer algorithm.
3. The method of claim 1, wherein one of the position and
orientation of the simulated scanner relative to the object defines
a scan plane and a rendering direction.
4. The method of claim 1, wherein the plurality of data values are
associated with a polygonal model of the object.
5. The method of claim 1, wherein the rendering the simulated
ultrasound image includes rendering a first set of data values from
the plurality of data values to a stencil buffer of a graphics
processor, and rendering a second set of data values from the
plurality of data values to a frame buffer of the graphics
processor, the first set of data values and the second set of data
values being associated with a polygonal model of the object.
6. A method, comprising: rendering a first set of data values to a
stencil buffer of a graphics processor; rendering a second set of
data values to a frame buffer of the graphics processor; and
applying an exclusive or (XOR) to the first set of data values to
identify a set of pixel values associated with one of an interior
and simulated interior of an object on an ultrasound scan plane,
the first set of data values and the second set of data values
being associated with a polygonal model of the object.
7. The method of claim 6, wherein the XOR is applied to the first
set of data values and the second set of data values via a stencil
buffer algorithm.
8. The method of claim 6, wherein the first set of data values and
the second set of data values are based on at least one of a
position and an orientation of a simulated scanner with respect to
the object.
9. The method of claim 6, the object being a simulated body
part.
10. The method of claim 6, further comprising: updating the first
set of data values and the second set of data values based on a
movement of the object.
11. The method of claim 10, the object being a simulated body part,
wherein the movement is a simulated movement based on a
physiological property of the simulated body part.
12. The method of claim 10, wherein the movement is based on a
manipulation of the object.
13. A method, comprising: receiving a first set of data values
associated with a position of a simulated scanner relative to an
object; receiving a second set of data values associated with the
position of the simulated scanner relative to the object, the
second set of data values different from the first set of data
values; applying via a stencil buffer algorithm an exclusive or
(XOR) to the first set of data values and the second set of data
values to identify a set of pixel values associated with one of an
interior and a simulated interior of the object; rendering a
polygonal model associated with the first set of data values to a
stencil buffer; and rendering the polygonal model associated with
the second set of data values to a frame buffer.
14. The method of claim 13, wherein the rendering the polygonal
model to the frame buffer includes using the stencil buffer as a
mask.
15. A processor-readable medium storing code representing
instructions to cause a processor to perform a process, the code
comprising code to: receive a plurality of data values associated
with a position of a simulated scanner relative to an object;
calculate, substantially in real-time, a plurality of image values
based on the plurality of data values; and render a simulated
ultrasound image in a graphical display based on the plurality of
image values, the simulated ultrasound image being representative
of one of an interior and a simulated interior of the object on the
ultrasound scan plane.
16. The processor-readable medium of claim 15, the code further
comprising code to: apply via a stencil buffer algorithm an
exclusive or (XOR) to the first set of data values to identify a
set of pixel values associated with one of a simulated interior and
an interior of the object; render a first set of data values from
the plurality of data values to a stencil buffer of a graphics
processor; and render a second set of data values from the
plurality of data values to a frame buffer of the graphics
processor, the first set of data values and the second set of data
values being associated with a polygonal model of the object.
17. A processor-readable medium storing code representing
instructions to cause a processor to perform a process, the code
comprising code to: render a first set of data values to a stencil
buffer of a graphics processor; render a second set of data values
to a frame buffer of the graphics processor; and apply an exclusive
or (XOR) to the first set of data values to identify a set of pixel
values associated with one of an interior and simulated interior of
an object on an ultrasound scan plane, the first set of data values
and the second set of data values being associated with a polygonal
model of the object.
18. The processor-readable medium of claim 17, further comprising
code to: update the first set of data values and second set of data
values based on a movement of the object.
19. The processor-readable medium of claim 17, the object being a
simulated body part, the code further comprising code to: update
the first set of data values and the second set of data values
based on a movement based on a physiological property of the
simulated body part.
20. The processor-readable medium of claim 17, further comprising
code to: update the first set of data values and the second set of
data values based on a manipulation of the object.
Description
BACKGROUND
[0001] The invention relates generally to graphical simulations,
and more particularly to a method and apparatus for simulating an
ultrasound image.
[0002] Ultrasound simulators allow medical professionals to gain
experience using ultrasound equipment in a realistic environment
without the need for live patients. Known ultrasound simulators
have been developed that simulate the functionality of conventional
ultrasound machines. In such simulators, a user manipulates a
simulated ultrasound probe over a mannequin, while simultaneously
viewing images captured from actual ultrasounds.
[0003] The images used in known ultrasound simulators are static
images recorded from actual ultrasounds performed on live patients.
Prior to the simulation, multiple images are taken at various
depths and locations, and are cataloged for later retrieval during
a simulation based on the manipulation of the simulated probe. The
major drawback of these simulators is their inability to simulate
dynamic situations (e.g., heart beat, breathing motions, palpation
of organs, etc.). The static images are played back in the same
manner regardless of the condition of the mannequin (i.e., whether
or not the mannequin simulates breathing, a simulation user
palpates the mannequin, etc.).
[0004] Other known simulators can produce independent static
three-dimensional image models that are based on actual ultrasound
images. The display of such models, however, is not based on use of
an ultrasound simulator.
[0005] Thus, a need exists for an ultrasound simulation device and
method that can produce ultrasound images based on dynamic models
in real time.
SUMMARY OF THE INVENTION
[0006] A method is disclosed that includes receiving data values
associated with a position of a simulated scanner relative to an
object. Image values are calculated, substantially in real-time,
based on the data values. A simulated ultrasound image is rendered
in a graphical display based on the image values. The simulated
ultrasound image is representative of an interior or a simulated
interior of the object.
[0007] In other embodiments, a method includes rendering a first
set of data values associated with a polygonal model to a stencil
buffer of a graphics processor and rendering a second set of data
values associated with the polygonal model to a frame buffer of the
graphics processor. A set of pixel values is identified to
represent one of an interior and a simulated interior of an object
on an ultrasound scan plane using an exclusive or (XOR) algorithm.
A simulated ultrasound image is rendered in a graphical display
based on the data values rendered to the stencil buffer. The
stencil buffer functions as a mask to actively assist rendering to
the frame buffer only pixels representative of the interior or
simulated interior of the object on the ultrasound scan plane.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic representation of an ultrasound
simulation device according to an embodiment of the invention.
[0009] FIG. 2 is simulated image produced by an ultrasound
simulation device according to an embodiment of the invention.
[0010] FIG. 3 illustrates a scan plane and a rendering direction
defined by a scanner position and orientation relative to a scanned
object according to an embodiment of the invention.
[0011] FIG. 4 is an example of applying an Exclusive Or (XOR)
algorithm to render an image to a stencil buffer.
DETAILED DESCRIPTION
[0012] A method is disclosed that includes receiving data values
associated with a position of a simulated scanner relative to an
object. Image values are calculated, substantially in real-time,
based on the data values. A simulated ultrasound image is rendered
in a graphical display based on the image values. The simulated
ultrasound image is representative of an interior or a simulated
interior of the object. The phrase "calculating substantially in
real time" is used to describe the updating of simulated ultrasound
images on a graphical display at a rate faster than the refresh
rate of the simulation. Thus, the images are updated as the
simulated scanner is passed over the object scanned, with little or
no delay. The phrase "calculating substantially in real time" does
not include, for example, loading a series of previously stored
images from a database.
[0013] Additionally, the phrase "dynamically updated" refers to the
updating of simulated ultrasound images in the graphical display
based on manipulation of the object being "scanned" and/or the
manipulation of the simulated scanner. Manipulation of the object
being scanned can include, for example, palpating the object, the
object simulating a physical deformation due to breathing
simulation or pulse simulation, etc. Manipulation of the simulated
scanner can include, for example, shaking the scanner, modifying
the view angle of the scanner, etc.
[0014] FIG. 1 is a schematic representation of an ultrasound
simulation device according to an embodiment of the invention. The
device 10 includes a simulated scanner 20 that is coupled to a
processor 30. The processor 30 is configured to output signals to a
display 40. An object 50 is coupled the processor 30 to send and
receive signals based on the condition of the object 50 and the
position of the scanner 20 relative to the object 50 as described
below.
[0015] The simulated scanner 20 is "simulated" in the sense that it
does not actually scan the object 50. As discussed in detail below,
images on the display 40 are output based on a location of the
simulated scanner 20 relative to the object 50 and not based on an
actual scan of the object 50. In other words, while the simulated
scanner 20 may be a functional ultrasound scanner in some
embodiments, it does not perform a scanning function as part of the
ultrasound simulation device 10. In other embodiments of the
ultrasound simulation device, the simulated scanner 20 is a
simulated scanner and is incapable of performing any scanning
function regardless of the system with which it is used.
[0016] The object 50 can be representative of a portion of a body
or an entire body. The object 50 may be an actual body part or a
simulated body part. Regardless of whether the object 50 is an
actual or simulated body part, object 50 does not affect the output
from the processor 30 because object 50 is not actually scanned.
The object 50 may be a mannequin or similar object shaped like a
human. The output of a simulated ultrasound image on the display 40
is not dependent upon the shape or other physical characteristics
of the object 50. In other words, the shape of the object need not
be representative of a human body for the output to be a simulated
representation of the interior of a human body.
[0017] Ultrasound simulation device 10 can have multiple modes of
operation. In one embodiment, a single object 50 (e.g., a single
box) may be used to represent multiple body parts. For example, in
one mode of operation, the object 50 can represent an upper torso
portion of a body and the displayed images can be associated with
the interior of the upper torso (e.g., heart, lungs, etc.). In a
second mode of operation, the object can represent a lower torso
portion of a body and the displayed images are associated with the
lower torso portion (e.g., the stomach, liver, etc.) accordingly.
In other words, a single position on the object 50 can be
associated with different images depending upon the operational
mode of the ultrasound simulation device 10. In some embodiments,
object 50 is not related to a body part. For example, object 50 can
be a crate or a simulated crate that may contain real or simulated
goods inside.
[0018] The display 40 is coupled to the processor 30 and is
configured to output a simulated ultrasound image (see, e.g., FIG.
2) based on data values associated with a position of the simulated
scanner 20 relative to the object 50. The processor 30 can be, for
example, a commercially available personal computer or a less
complex computing or processing device that is dedicated to
performing one or more specific tasks. For example, the processor
30 can be a terminal dedicated to providing an interactive virtual
reality environment, such as a gaming system, or the like.
[0019] The processor 30, according to one or more embodiments of
the invention, can be a commercially available microprocessor.
Alternatively, the processor 30 can be an application-specific
integrated circuit (ASIC) or a combination of ASICs, which are
designed to achieve one or more specific functions, or enable one
or more specific devices or applications. In yet another
embodiment, the processor 30 can be an analog or digital circuit,
or a combination of multiple circuits.
[0020] The processor 30 includes a memory component (not shown in
FIG. 1). The memory component can include one or more types of
memory. For example, the memory component can include a read only
memory (ROM) component and a random access memory (RAM) component.
The memory component can also include other types of memory that
are suitable for storing data in a form retrievable by the
processor 30. For example, electronically programmable read only
memory (EPROM), erasable electronically programmable read only
memory (EEPROM), flash memory, as well as other suitable forms of
memory can be included within the memory component. The processor
30 can also include a variety of other components, such as for
example, co-processors, graphics processors, etc., depending upon
the desired functionality of the device 10.
[0021] The processor 30 is in communication with the memory
component, and can store data in the memory component or retrieve
data previously stored in the memory component. The components of
the processor 30 can communicate with devices external to the
processor 30 by way of an input/output (I/O) component (not shown
in FIG. 1). According one or more embodiments of the invention, the
I/O component can include a variety of suitable communication
interfaces. For example, the I/O component can include, for
example, wired connections, such as standard serial ports, parallel
ports, universal serial bus (USB) ports, S-video ports, large area
network (LAN) ports, small computer system interface (SCSI) ports,
and so forth. Additionally, the I/O component can include, for
example, wireless connections, such as infrared ports, optical
ports, Bluetooth.RTM. wireless ports, wireless LAN ports, or the
like.
[0022] The processor 30 is configured to send and receive signals
to and from the object 50 and the simulated scanner 20. The
processor 30 receives data values associated with the position of
the simulated scanner 20 relative to object 50. The position
signals can be received from either the simulated scanner 20 or the
object 50. The position of the simulated scanner 20 can be
measured, for example, as a relative distance and direction from a
predetermined reference point. The reference point can be a point
on or in the object 50 or some other location in the device 10. For
example, if the object 50 is configured to be positioned on a
support (not shown), the reference point can be on the support. In
alternative embodiments, a sensor or multiple sensors (not shown)
can be disposed in the object that are configured to detect the
location of the simulated scanner 20 with respect to the object 50.
Alternatively, the object 50 can include a wireless or wired
transmitter (not shown) that sends a position signal to the
simulated scanner 20 to determine position information of the
simulated scanner 20 relative to the object 50.
[0023] It is desirable for the position of the simulated scanner 20
relative to the object 50 to be coordinated in a realistic sense
with respect to the images output on the display 40. For example,
when the object is a simulated human body, the images output on the
display 40 should be the relevant portion of the interior of the
body corresponding to the position of the scanner 20 (e.g., when
the simulated scanner 20 is positioned above the simulated location
of the heart, an image of a heart is output on the display 40).
[0024] As the simulated scanner 20 is moved from one position to
another, the images output on the display 40 are dynamically
updated substantially in real time as will be described below. In
some embodiments of the invention, the simulated scanner 20 is
provided in a fixed location and the object 50 is movable with
respect to the simulated scanner 20. When movement of the simulated
scanner 20 is discussed herein, the movement is a relative movement
with respect to the object 50. Movement of the object 50 relative
to the simulated scanner 20 provides output similar to the output
produced when the simulated scanner 20 moves.
[0025] The processor 30 is capable of calculating, substantially in
real time, image values based on the data values associated with
the position of the simulated scanner 20 relative to the object 50.
The simulated ultrasound image is rendered graphically on the
display 40 based on the calculated image values. The simulated
ultrasound image is representative of an interior or a simulated
interior of the object 50 on the ultrasound scan plane. In other
words, where the displayed simulated ultrasound image represents an
actual interior of the object 50 being used with the ultrasound
simulation device 10, then the simulated ultrasound image is
representative of the actual interior of the object 50.
[0026] Referring to FIG. 3, when the simulated scanner 20 is
positioned adjacent the object 50, a scan plane is defined based on
at least one of the position and orientation of scanner 20 relative
to the object 50. During the process of rendering an image to the
stencil buffer or the frame buffer, the rendering direction is
defined as being substantially perpendicular to the ultrasound scan
plane.
[0027] The rendering of simulated ultrasound images can first be
performed by a stencil buffer algorithm based on a computer
graphics language, for example, Open GL or DirectX. FIG. 4
illustrates how the Exclusive Or (XOR) stencil buffer algorithm can
identify the pixels that represent an interior of a scanned object
on the scan plane. Some polygonal models representing scanned
objects are stored in processor 30. When the scan plane is used as
the far clipping plane to render to models to the stencil buffer
using an XOR algorithm, only those pixels that represent the
interior of the scanned object on the scan plane will be written an
odd number of times. Referring to FIG. 4, for example, the pixels
in the stencil buffer corresponding to lines a, b, c, d, e are
written 0, 2, 3, 1, 2 times, respectively. Since pixels c and d are
written an odd number of times, they are identified as among the
interior pixels of the scanned object on the scan plane.
[0028] Various polygonal models corresponding to the displayed
image are defined such that the simulated scanner 20 is
perpendicular to a cutting plane (i.e., the plane parallel to the
scan plane) of the object 50. The polygonal models are rendered to
a stencil buffer with, for example, stencil buffer settings: [0029]
glClearStencil(0.times.0); [0030] glClear(GL_STENCIL_BUFFER_BIT);
[0031] glStencilFunc(GL_NEVER, 0.times.1, 0.times.1); [0032]
glStencilOp(GL_INVERT, GL_KEEP, GL_KEEP). Pixels that are
represented as a cross section (i.e., have a visible portion of the
scanned simulated interior of object 50) have a value of "1" in the
stencil buffer matrix.
[0033] Next, the polygonal models are rendered to a frame buffer
with the stencil buffer enabled as a mask. Any pixel with a stencil
buffer value of 1 can be written and any pixel with a stencil
buffer value of 0 is masked or blocked from being written. An
ultrasound texture can be used with this round of rendering to give
the rendered image a more realistic appearance. The texture can be
captured, for example, from actual ultrasound images. The stencil
buffer is enabled with, for example, the settings: [0034]
GlEnable(GL_STENCIL_TEST); [0035] glStencilFunc(GL_NOTEQUAL,
0.times.0, 0.times.1); [0036] glStencilOp(GL_KEEP, GL_KEEP,
GL_KEEP).
[0037] The ultrasound fan-shaped mask is then drawn to the stencil
buffer and the frame buffer based on the calculations of the
interior and the boundary of the displayed image.
[0038] Using the method described above, substantially real-time
updates of the simulated ultrasound image are rendered. As the
position of the simulated scanner 20 changes, the image dynamically
changes. Additionally, the position of the simulated scanner 20 can
be maintained while the image is dynamically updated based on
movement of the object 50 or simulated movement of the object 50.
For example, a mannequin representing a human body can be
configured to simulate human breathing and cardiac functions. Thus,
when the heart or lungs are being scanned, the simulated ultrasound
image will change with the simulated movement of the scanned moving
organ even though the position of the simulated scanner 20 does not
change with respect to the object 50.
[0039] Additionally, the object 50 can be physically moved. For
example, if the object 50 is being used as a palpation simulator,
when a user pushes down on the object 50, the simulated organ being
scanned can change in shape. Accordingly, the simulated ultrasound
image is updated based on the change in distance between the object
50 and the simulated scanner 20. Palpation simulators incorporating
haptic feedback devices are described in U.S. application Ser. No.
09/848,966, filed May 4, 2001, which is incorporated herein by
reference in its entirety.
CONCLUSION
[0040] While various embodiments of the invention have been
described above, it should be understood that they have been
presented by way of example only, and not limitation. Thus, the
breadth and scope of the invention should not be limited by any of
the above-described embodiments, but should be defined only in
accordance with the following claims and their equivalence.
[0041] The previous description of the embodiments is provided to
enable any person skilled in the art to make or use the invention.
While the invention has been particularly shown and described with
reference to embodiments thereof, it will be understood by those
skilled in art that various changes in form and details may be made
therein without departing from the spirit and scope of the
invention.
[0042] For example, although the simulated scanner 20 is
illustrated as being external to the object 50, in an alternative
embodiment the simulated scanner can be an internal scanner and can
be inserted in the object.
[0043] Although the processor 30 is described above as being
directly coupled to the simulated scanner 20 and the simulated body
part, in an alternative embodiment, the processor can be coupled to
the ultrasound simulation device 10 via a network.
[0044] Although the device as described above is used with a
simulated body part, in an alternative embodiment, the device is
used for simulated scanning of objects such as boxes, crates,
etc.
* * * * *